Electrodeposition of metals



atented New, 20, 3945 sprain arrin Henry Brown, Kansas (Jity, Mm, assignor to The Udylite Corporation, Detroit, Mich, a corporatlcn of Delaware No Drawing. Application May 15, 1941, Serial No. 393,662

16 Claims.

My invention relates to improvements in the electrodeposition of metals. It is particularly concerned with the utilization of certain addition agents, for the purposes hereinafter stated, in aqueous acidic electroplating baths.

I have discovered that certain substances, hereinafter described in detail, when added to electroplating baths, particularly aqueous acidic electroplating baths such as used for the electrodeposition of nickel, cobalt, iron, zinc, cadmium, COP'. per, antimony, various alloys containing the aforementioned and other metals, and the like. are remarkably effective in the prevention of the formation of pits in the electro-deposited coatinss, said pits normally being caused by the adherence of gas bubbles during the electrodeposition of the coating. I have found, further, that this result is accomplished despite the fact that very low concentrations of the addition substances are employed and, still further, that these results are accomplished without causing any significantly appreciable interference with the desired appearance, structure, and character of the plate.

I have also discovered that the addition agents are highly efiective independently of whether various organic or inorganic so-called brightenvarious suggested anti-pitting agents have proven entirely unsatisfactory. The use of the addition agents in bright plating baths represents but one aspect of my present invention although, to be sure, a highly important one.

The addition agents which I have found to be unusually satisfactory, in accordance with my present invention, can be used in sufllciently low concentrations so as to reduce substantially, or eliminate entirely, pitting oi the deposits and, at the same time, they do not interfere to any significantly appreciable extent with the particular cathodic process involved such as reduction of inorganic or organic substances taking place in the process of electrr-depositing the coating. This is highly important where the deposited metal is desired not only free from pits but also of maximum ductility and purity and freedom from such inclusions as sulphur, carbon and colloids. It is also of considerable importance in those cases involving bright plating baths, particularly aqueous acid plating baths for the electroplating of nickel, which baths contain brighteners such as those mentioned hereinabove, particularly those wherein the brightener is in the formof a soluble compound containing the radical SO2.N=. As I have pointed out hereinabove, the brightness or brilliance or high luster of the deposits is not adversely affected where the addition agents, to which my present invention relates, are employed. 1 p

The novel and highly useful addition agents which accomplish the functions set out hereinabove are, in general, aliphatic alkyl ether sulionates containing at least 8 carbon atoms, preferably containing an alkyl chain of 8 to 18 can .the order of about 0.05 to about 0.5 gram per liter of electrolyte solution, from about 0.1 to about 0.3 gram per liter of electrolyte solution being most satisfactory in the usual case. More addition agent may be utilized but it is, in general, uneconomic to do so arid iully satisfactory results are obtained in practically all cases "with the preferred range set out hereinabove.

(l) OHS-(CHQIPGBr-O-CHFSOaNB l-oxydodecyl-l-sodium sullonste-methane l-(dodecyloxyethyl) oxy-Z-sodium sulfonate ethane l glycerol and mixtures thereof carbohydrates and H on sugars such as dextrose, sucrose, and maltose; and sugar alcohols such as arabltol, mannitol. filoggfi' sorbitol, dulcitol, mannitan and sorbitan, and

. the like 8 (8) cHr-(cm'rcfiro 0 The alkyl radicals of the addition agents may l-(dodecyioxydiethyl) oxy-2-potassium sullonate ethane be selected from a large group including, by way 9) CH3-(CH2)io'CH:O CH2(CHOH)|CH:SO3N1\ of example, hexyl, heptyl, octyl, nonyl, decyl, un-

l-oxydodecyl-2,3,4,5-tetrahydroxy-6-sodium y la yl, myristyl, cetyl, oleyl, linoleyl, Sulfonate hexane stearyl, ricinoleyl, palmitoleyl; branched chain CHS' (CHI)H CHTO'CHICHTSOQNB alkyl such as 2-ethyl hexyl, 2-n-butyl octyl, 2-

l-oXycety1-2-sodium sulionate ethane butyl tetradecyl, and the like.

(l1) Glenn-CH-CH1O'-CQHA -C2HLSQ NB It will be understood that the addition agents H utilized should be soluble in the electrolyte solution at least to such an extent as to fall within ";$2,Z the general range as set out hereinabove. In

general, the solubility of the addition agents in am-(CH1)n-CHe-O-CHrCH-CHrO-CH CE-CH SQ,Ne the electrolyte solutions decreases with the increase of carbon atoms in the alkyl chain ofthe H H addition agents and, therefore, lower concentra- 1-(i-ox dodeo i-ah croxypro yl)oxy-2-hvdroxytions of such addition agents may be used. Consflmm'pmpam versely, higher concentrations, generally speak- (mi-(CB1)ir-CH1-CHr-(CHH)4CHF503K ing, of those addition agents should be used l-oxydodecyl-Z, 3, 4, 5-tetrahydroxy-fi-potessium sullonatc Where the number carbon atoms n the alkyl 11mm chain is around 8 to 10 carbon atoms. The ad- (14) CHt(CHt)tCHtOCH,(CHOH)iCH,soti e dition agents which are preferably employed, as

indicated hereinabove, are those having an alkyl t b t 2 3 dmydmflfldmm 9 chain containing from 10 to 16 carbon atoms and (15) CHr-(CHI)r-CHT-O(CIHi-O)PQHPSOZNB of particular utility are those having an alkyl l-(decyloxytriethyl)-2-scdium sulionate ethane chain containing predominantly 12 to 14 carbon (16) cm-(crh)woHr-o-cm-on-cm-soem atoms, the lauryl ether derivatives being espe- 'i b l t f th 1 a e I se 5 or var ous examples of plating baths with which the addition agents of the some o e addition a of the Present 3 present invention may be used effectively to prevention may be represented by the general vent or inhibit pitting. It will be understood formula that these examples are merely illustrative and (s atrebniot to be1 talendasullintiitative of mly i ti'linventioni eng un ers 00 a in genera, e nove wherein R15 an alkyl (including hydroxy'alkyl) 40 teachings of my invention may be utilized in radical ntam1ng at least 6 in connection with plating baths wherein the addithe usual case from 6 13 carbon atoms, x is tion agents are soluble in the electrolyte soluthe residue of an aliphatic polyhydmxy tions to the extent necessary to accomplish the stance, is a cation, the sulphur of the grou desired results, and wherein said addition agents bemg linked directly to carbon of and are not hydrolyzed or otherwise decomposed or t and w are each integers Preferably modified to an extent suflicient to interfere with various of the addition agents of the present their functioning. In general, the addition invention may also be represented by the general agents are particularly effective in aqueous formula acidic electroplating baths wherein the pH of R0(CHi)t s the bath is of the order of about 2 to about 6.

wherein R is an aliphatic radical including or Table 1 comprising an alkyl (including hydroxy-alkyl) radical having at least 6 carbon atoms, in the In each bath gram/liter 9131-0-07 usual case from 6 to 18 carbon atoms, 11 is an in- 0f the compwnd 0f Example teger such as 1, 2, 3, 4 or more, and Y is a cation such as those mentioned hereinabove. Cone. Cone. As I have indicated hereinabove and illustrated Nickel (white) Nickel (white) by some of the examples, various of the addition a ents which I hav dis los m y b considered ti otft nl fiii: 8 %'6?.?.91::11311111 as derivatives of aliphatic polyhydroxy subreplaced by sulphonic radicals and wherein the e Cathode 5-150 hydrogen of at least one hydroxy group of the ampl aliphatic polyhydroxy substances is replaced by an alkyl or hydroxy-alkyl radical containing at least 6 carbon atoms and preferably from 12 to Nickel (hrigbt) Cobalt 14 carbon atoms. Among the water-soluble aliphatic polyhydrcxy substances, the aforementioned specific derivatives of which are included 83 05262281111: among the addition agents of my present invengg 0 2 tion, are, for example, glycerin; glycols such as m ethylene glycol, propylene glycol, trimethylene ga ja- 9g? Egg;- P glycol, and the like; poiyglycols such as diethyl- Cathode 6.15.3535 .II Cathode IIIIIIII ene glycol, triethylene glycol, and the like; polyamp/m glycerols such as diglycerol, triglycerol, tetraaasaiai Nickel-cobalt 00110., Zinc 00110., (bright) ozJgal. ozJgal.

NiSO .0-7Hg0 32 ZnSO4.7H1O... 30-40 0080411330.-. 8 ZD(C:H303)Q. 4 NiCl .6H 0. 2 1( a)ao 0 I Temp. loo-150 F Temp. loo-150 F pH-=4.0-5.5 pH=4.0-5.5 Cathode C. D. -100 Cathode C. D. -50

amp/it. amp/it.

Cone, Conc., Iron oz./gal. Copper ozJgal.

F60]: 4O CDSQ4.5H9O CECILGHH) 20 Cl1(C:H30z)7.. Temp. loo-150 F Temp. 70150 pH-3.55.0 pH=3.0-5.0 Cathode C.D. 10-100 Cathode C. D. 10-50 amp/it. amp/it.

Nickel (white) nga- Copper NiS0.6-7H:O 40 01180451120 30 NiClqfiHzO -6 H2804 5 H3130: I

Temp. loo-180 Temp. 80-160 F pH=l.5-2.5 pH=l.0-l.5

Cathode C. D. 20-100 Cathode C. D. 20-100 amp/it. amp/ft! While, in the examples listed hereinabove in Table I, Ihave disclosed the use of the compound of Example 1 as the addition agent, it will be understood that others of the addition agents which I have disclosed may be substituted therefor without in any manner departing from the spirit and teachings of my invention.

It will be understood that, from time to time, more addition agent should be added to replenish that which is lost by drag-out" or which may possibly be changed, in some manner or other, during the electrodeposition process.

What I claim as new and desire to protect by Letters Patent oi the United States is:

1. In a process of electrodepositing metals, the step which comprises electrolyzing an aqueous acid solution of a salt of the metal to be deposited and a minor proportion of a soluble aliphatic alkyl ether sulfonate containing an alkyl radical having a chain of from 6 to 18 carbon atoms, the metal to be deposited being selected from the group consisting of nickel, cobalt, .iron, zinc, cadmium, copper, and antimony.

2. In a process for electrodepositing metals, the step which comprises electrolyzing an aqueous acid solution of a salt of the metal to be deposited and a minor proportion of a soluble aliphatic alkyl ether sulfonate containing straight chain alkyl radical of 12 carbon atoms, the metal to be deposited being selected from the group consisting of nickel, cobalt, iron, zinc, cadmium, copper, and antimony.

3. In a process for electrodepositing metals, the step which comprises electrolyzing an aqueous acid solution of a salt of the metal to be deposited and a minor proportion of a soluble aliphatic alkyl ether sulfonate corresponding to the formula wherein R is an aliphatic radical comprising an alkyl group of from 6 to 18 carbon atoms, a is an integer, and Y is a cation, the metal to be deposited being selected from the group consisting of nickel, cobalt, iron, zinc, cadmium, copper, and antimony.

4. In a, process of electrodepositing nickel, the step which comprises electrolyzing an aqueous acid nickel solution containing a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, said aqueous solution also containing a minor proportion of a soluble aliphatic alkyl ether sulfonate containing at least 8 carbon atoms.

.5. In a process of electrodepositing nickel, the step which comprises electrolyzing an aqueous acid nickel solution containing a material selected from the grou consisting of nickel sulphate, nickel chloride, and mixtures thereof, said aqueous solution also containing a minor proportion of the compound where Y is an alkali metal cation.

6. In a process of electrodepositing metals,-the step which comprises electrolyzing an aqueous acid solution of a salt of the metal to be deposited, said solution containing from about 0.1 to about 0.5 gram per liter of a soluble aliphatic alkyl ether sulfonate containing an alkyl group with from 6 to 18 carbon atoms, the metal to be deposited being selected from the group consisting of nickel, cobalt, iron,-zinc, cadmium, copper, and antimony.

7. A bath for the electrodeposition of metals comprising an aqueous acid solution of a compound of a metal to be deposited by electrolysis and a minor proportion of a soluble aliphatic alkyl ether sulfonate having an alkyl chain of from 12 to 14 carbon atoms, the metal to be deposited being selected from the group consisting of nickel, cobalt, iron, zinc, cadmium, copper, and antimony.

8. A bath for the electrodeposition of metals comprising an aqueous acid solution of a compound of a metal to be deposited by electrolysis and from about 0.1 to about 0.5 gram per liter of an aliphatic alkyl ether sulfonate containing a straight chain alkyl radical of from 12 to 14 carbon atoms, the metal to be deposited being selected from the group consisting of nickel, cobalt, iron, zinc, cadmium, copper, and antimony.

9. A bath for the electrodeposltion of nickel comprising an aqueous acid solution of a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, and a minor proportion of a soluble aliphatic alkyl ether sulfonate the alkyl radical of which contains from 8 to 18 carbon atoms.

10. A bath for the electrodeposition of nickel comprising an aqueous acid solution of a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, and a minor proportion of the compound wherein Y is an alkali metal cation.

also containing mi or pro ortions or a soluble aliphatic alkyl ethemman alkyl-group having from 6 to 18 car ms.

12. In a process of electrodepositing nickel to obtain a bright or lustrous deposit, the step which prising an aqueous acid solution of a material selected from the group consisting of nickel suiphate, nickel chloride, and mixtures thereof, and minor proportions of a soluble aliphatic lauryl ether sulionate.

14. A bath for the electrodeposition of nickel in the form of a bright or lustrous deposit, comprising an aqueous acid solution of a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, and minor proportions of a soluble aliphatic lauryi ether sulfonate and a brightener in the form of an aromatic compound soluble in the solution and containing the group SO2.N=.

15. In the process of electrodepositing metals, the step which comprises electrolyzing an aqueous acid solution of a salt of the metal to be deposited and a minor proportion of a soluble aliphatic alkyl ether sulionate corresponding to the formula:

wherein R is an alkyl radical containing from 6 to 18 carbon atoms, X is the residue of an aliphatic polyhydroxy substance, Y is a cation, the sulphur of the group SOaY being linked directly to carbon or X, and t and w are each integers, the metal to be deposited being selected from the group consisting of nickel, cob'alt, iron, zinc, cadmium, copper, and antimony.

16. A bath for the electrodepositing of metals comprising an aqueous acid solution of a compound of the metal to be deposited by electrolysis and a minor proportion of a soluble aliphatic alkyl ether suifonate corresponding to the formula:

wherein R is an alkyl radical containing from 6 to 18 carbon atoms, X is the residue of an allphatic polyhyclroxy substance, Y is a cation, the sulphur oi the group SOsY being linked directly to carbon of X, and t and w are each integers, the metal to be deposited being selected from the group consisting of nickel, cobalt, iron, zinc, cadmium, copper, and antimony.

HENRY BROWN. 

